The purpose of this project is to study heme arginate for the treatment of the acute porphyrias (acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria). Heme arginate (Normosang, Leiras) is a stable heme preparation for intravenous use that was developed and studied in Europe for acute porphyrias, but has not been available in the United States. The heme preparation currently approved by the FDA as an orphan product for the treatment of these disorders has a number of disadvantages, including poor chemical stability, a short shelf life and troublesome side effects such as coagulation abnormalities and phlebitis at the site of intravenous infusion. These features have limited the application of heme treatment in porphyria patients in the United States. Therefore, availability of heme arginate would be a distinct advantage to patients with these disorders. The aims of these proposed studies are 1) to determine the safety and efficacy of heme arginate in 20 patients with acute attacks of porphyria in terms of producing remissions of symptoms and lowering porphyrin precursors; 2) to study the value of heme arginate infusions for the prevention of frequently occurring attacks of porphyria in up to 15 patients. 3) to carry out dose-ranging studies of effects of heme arginate on reducing porphyrin precursor levels in 12 stable patients with acute intermittent porphyria. These multicenter studies will provide a basis for considering approval of heme arginate as an orphan product in the United States for the treatment and for the prevention of attacks of the acute porphyrias.